.editor {
  margin: auto;
  width: 800px;
  height: 500px;
}

.editor-pre {
  box-sizing: border-box;
  padding: 5px;
  width: 800px;
  height: 500px;
  border: 1px solid black;
}

pre{
  white-space: pre-wrap;
  word-wrap: break-word;
  padding: 10px;
  margin: 0;
  box-sizing: border-box;
}

.preview {
  background-color: #fafbfc;
  border-left: 2px solid #ddd;
}

.preview strong {
  font-weight: bold;
}

.preview em {
  font-style: italic;
}

.preview del {
  text-decoration: line-through;
}